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Brake light question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by weisel, May 22, 2002.

  1. weisel

    weisel 1/2 ton status

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    What is the part that needs fixing or replaceing when the brake light comes on only when I push hard on the peddal, and goes off when I let up and push it down again?
     
  2. shane74

    shane74 1/2 ton status

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    Mine does that when I have to mash on the brakes and the pads and/or fluid is low. I don't know exactly what causes it, but I do know that it goes away when I add fluid if it has gotten low, or when I replace the front brake pads.
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    Could be a few things (low fluid, etc) but mine was master cylinder.

    That doesn't mean I'm saying replace it without making sure the brakes are bled correctly, the fluid level is correct, there are no leaks in the system, etc.
     
  4. Triaged

    Triaged 1/2 ton status

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    When the brake light comes on it means you have a hydrolic leak somewere. I would not drive it untill I got it fixed.
    The first place I would check is the wheel cylinders. You have to remove the wheel drum and pry back the dust boots to see if they are leaking. The front is easier to check because the calipers are more in the open. Same thing goes with them...you have to pry back the dust boot to see if they are leaking. The master cylinder can leak 2 ways and both of them you can't see. It will either have a internal leak (leak bace into the res.) or it will have a external leak (leak into the booster and get sucked into the motor).
     
  5. BozoWise

    BozoWise 1/2 ton status

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    Mine came on after my axel swap and I had to bleed the brakes multiple times to get it to go off. But the air in the lines was making it go on.
     
  6. 89Blazin

    89Blazin 1/2 ton status

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    Brake lights for the truck, or BRAKE light in the dash?
     
  7. Mudstud

    Mudstud 1/2 ton status

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    I've gone round and round with this a while back. Had it happen a couple times exactly as you described. Definetly check all your pads and shoes and replace if needed. The second thing to consider is mis adjustment in the rear drums. If you don't back up very often or back up slowly eventually the brakes will become out of adjustment. AFTER inspecting the pads and shoes, try backing up on asphalt and slamming the brakes. Then do it a again and again and again to see if there is any change. NOTE: after a long day wheelin I always back up several times to adjust the brakes. I can always tell a difference in the peddle.
     
  8. marv_springer

    marv_springer 1/2 ton status

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    I'm assuming that the "brake light" that comes on is in the dash. If so, replace the master cyl...

    The reason it's coming on is because the proportioning valve senses a large difference in the two sides of the master cylinder.

    Marv
     

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